1,720,954 research outputs found
Bidirectional control of dorsomedial striatum on innate avoidance behavior
Full text linkAvoidance behaviour, aimed at escaping dangerous stimuli and threatening situations, can become maladaptive when individuals avoid relatively safe situations, a hallmark of anxiety disorders. Innate avoidance, a natural aversion to ethologically relevant stimuli, involves a neural circuit in which the basolateral amygdala (BLA) and prefrontal cortex (PFC) play a central role. We have observed that both the PFC and the BLA send converging unidirectional excitatory inputs to the dorsomedial striatum (DMS), which thus may be ideally positioned to regulate the output of this circuit. Indeed, the DMS has been implicated in learned, and more recently in innate avoidance behaviours. To investigate the role of the PFC-DMS and BLA-DMS pathways in innate avoidance, we used a chemogenetic approach. CD1 male mice received a bilateral injection of AAVs expressing either the inhibitory DREADD hM4D(Gi) or the excitatory DREADD hM3D(Gq) in the PFC or BLA. Then, mice were focally injected with CNO or saline into the DMS and tested in the elevated plus maze (EPM) 30 minutes later. Inhibiting the PFC-DMS pathway did not affect the time spent in open arms of the EPM, but its activation significantly reduced anxiety. On the other hand, activation of the BLA-DMS pathway led to a reduction in the time spent in the open arms, while its inhibition had a strong anxiolytic effect. To understand why the same type of manipulation of two pathways converging in the same region generates opposite behavioral responses, we aimed to evaluate the contribution of striatal interneurons receiving direct projections from the PFC or the BLA. To this end, Ai14 mice were injected in the PFC or BLA with an anterograde virus (AAV1-hSyn-P2A-Cre-WPRE), capable of crossing the downstream synapse and infecting neurons that receive input from neurons at the injection site. Subsequently, brain sections were processed with a parvalbumin antibody to identify the percentage of double-positive striatal interneurons and verify whether a different percentage of these neurons received projections from the PFC or BLA. However, we did not observe significant differences in the percentage of parvalbumin-positive striatal interneurons receiving input from the PFC or BLA. As a final experiment, to verify how information from the PFC and BLA flows downstream of the basal ganglia, CD1 mice were injected with a viral vector expressing channelrhodopsin, while optical fibers were implanted in the GPi to specifically manipulate this projection during the EPM and OF tests. Activation of this pathway showed a reduction in time spent in the open arms of the EPM, suggesting an increase in avoidance behavior, without altering locomotion as measured in the OF. These results not only confirm the involvement of PFC-DMS and BLA-DMS projecting neurons in mice behaviour in the EPM, but also underscore that these pathways exert opposing bidirectional control over innate avoidance. Moreover, additional experimental subjects will be necessary to confirm the opposite effect of the projections does not involve a different contribution of parvalbumin-positive interneurons. Finally, this is the first evidence that information arriving in the DMS, which mediates avoidance behaviors, flows downstream to the GPi
Specific patterns of neural activity in the hippocampus after massed or distributed spatial training
Full text linkAbstract Training with long inter-session intervals, termed distributed training, has long been known to be superior to training with short intervals, termed massed training. In the present study we compared c-Fos expression after massed and distributed training protocols in the Morris water maze to outline possible differences in the learning-induced pattern of neural activation in the dorsal CA1 in the two training conditions. The results demonstrate that training and time lags between learning opportunities had an impact on the pattern of neuronal activity in the dorsal CA1. Mice trained with the distributed protocol showed sustained neuronal activity in the postero-distal component of the dorsal CA1. In parallel, in trained mice we found more active cells that tended to constitute spatially restricted clusters, whose degree increased with the increase in the time lags between learning trials. Moreover, activated cell assemblies demonstrated increased stability in their spatial organization after distributed as compared to massed training or control condition. Finally, using a machine learning algorithm we found that differences in the number of c-Fos positive cells and their location in the dorsal CA1 could be predictive of the training protocol used. These results suggest that the topographic organization and the spatial location of learning activated cell assemblies might be critical to promote the increased stability of the memory trace induced by distributed training
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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